This study investigates municipal waste incineration ashes as an alternative binder in mortar. The investigations include chloride removal by washing, binder preparation by milling and mortar testing. The objective is to investigate the strength and leaching properties of the ash-based binder system. The ashes are from Jönköping energy; tests are carried out in the laboratory at University of Borås and NG Nordic AB. 

The washing process is demonstrated on two bottom ash fractions, a coarse fraction (12/30 mm) and a fine fraction (0/12 mm). With an initial chloride content of approximately 0.6%, washing is most effective for the fine fraction, reducing chloride levels to 0.14%, below the SS-EN 206 limit of 0.2%. The coarse fraction reaches 0.39% chloride after washing and can therefore be used at up to approximately 30% cement replacement to remain within the 0.2% standard limit. The washing process is effective in reducing the leachability of chlorides. 

A preliminary trial on mechanical activation of the washed ash is attempted using micro-deval apparatus. The resulting ash is coarser than cement, with a median size between 90-100 µm compared to 10 µm median particle size for cement.

A 30% cement replacement with ash is investigated in mortar specimens. Compressive results at 7 and 28 days is 30% of the reference mortar at respective ages. The compressive strength shows improvement with ternary binder combination of 30% ash, 20% blast furnace slag and 50% cement. Resulting in 42% of the reference strength at 7 and 28 days respectively. This indicates synergistic effects of slag along with ash, an interesting question for future research.